In the retail trade, items are usually bought in bulk for delivery to a central warehouse. From this central warehouse, the items are then distributed to individual retail branches or retail stores. For this purpose, the items, shipped by the manufacturer to the central warehouse in large shipment or packaging units of single-type items, must be repackaged into shipping or packaging units which are smaller and/or composed of mixed items for transport to the retail stores or retail branches. The shipping or packaging units of single-type items that are delivered to the central warehouse are therefore hereinafter referred to as inbound units, while the mixed assembled items leaving the central warehouse in the direction of the retail outlets are called outbound units. The aforementioned process of repacking and assembling items, which is commonly known as order picking, thus comprises the unpacking of an inbound unit of single-type items and the assembling of different items to form an outbound unit. The following description thus relates more generally to any process in which operations resembling order picking have to be performed.
The example of returnable beverage crates affords a simple way of illustrating the process of order picking. A brewery, for instance, delivers its various beverages, sorted by type, on standardized euro pallets, its smallest shipping or packaging units, as an inbound unit. Such an inbound unit is too large for delivery to retail stores, since the retail stores or branches have neither enough storage space for correspondingly large amounts of one type of beverage nor sufficient sales of the corresponding beverages that would render it profitable to store large quantities of different varieties of beverages. Thus, stocks of a single type of a returnable beverage in retail grocery stores are often limited to a few crates of that type. Accordingly, somewhere in a central warehouse for supplying the retail grocery stores or branches with an inbound unit (e.g., in the form of a standardized euro pallet), mixed types of beverages have to be assembled on the standardized euro pallet. Hitherto, it was customary to manually re-stack the pallets. This entails breaking the single-type pallet stacks in the central warehouse and assembling individual pallet stacks for individual stores or branches to suit their needs. Due to the great weight of the beverage crates, this is hard physical work, which also incurs a high personnel and organizational burden.
Automated order picking of returnable beverage crates has failed so far because returnable beverage crates are hard to identify. The lack of identifiability results from the fact that the distinguishing features mostly relate to the beverage manufacturer only, and not to the different types of beverages which the beverage company offers in single-type beverage crates. Thus, while the returnable beverage crates usually bear the name of the beverage company and are decorated in the manufacturer's typical color, the beverage crates themselves bear no information concerning these beverages because the crates are intended to be used for various types of beverages. On account of the multiple distribution channels and the swapping of returnable beverage crates among numerous different market participants, the attachment of a clearly identifiable marking is very difficult because it is necessary to ensure that a beverage crate which makes several rounds with different types of beverages always bears just one correct marking. This gives rise to the problem that either not all previously attached identifying markings are 100% removed or the effort involved in 100% replacement of the identifying markings is very high.